细菌二叶酸减少酶的原子分辨率晶体结构中的X射线驱动化学和形状异质性
Nathan Smith1, Alexander R Horswill2, Mark A Wilson1
1Department of Biochemistry and Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE, 68588.
bioRxiv : the preprint server for biology
|November 21, 2023
概括
X射线可以意外地驱动细菌二叶酸减少酶 (DHFR) 酶中的化物转移,类似于它们的自然催化功能. 这一发现揭示了X射线光还原作为研究酶动态和抗生素点的工具.
科学领域:
- 生物化学 生物化学
- 结构生物学 结构生物学
- 酶催化酶的催化作用
背景情况:
- 二叶酸减少酶 (DHFR) 是叶酸代谢中的关键酶,对于DNA合成至关重要.
- 细菌DHFRs是经过验证的抗生素标,这使得它们对抗菌药物开发至关重要.
- 蛋白质的结构动力学在酶催化中发挥着关键作用,但研究起来具有挑战性.
研究的目的:
- 通过使用X射线晶体学研究蛋白质结构动力学在细菌DHFR催化中的作用.
- 探索X射线辐射是否可以诱导DHFR-联结体复合体中的催化活性.
- 为了比较 *Bacillus subtilis* (Bs) DHFR 和 *E. coli* (Ec) DHFR 的结构和动态差异.
主要方法:
- 从* Bacillus subtilis* 和 * E. coli* DHFRs收集了高分辨率 (0.93 Å) 的X射线衍射数据.
- 形成了DHFR与叶酸和NADP+的氧化三元复合体.
- 分析了电子密度图,以检测在不同X射线剂量下化物转移和形状变化.
主要成果:
- 电子密度图显示,化物转移发生在B. subtilis和E. coli的DHFR复合体中,尽管它们处于非反应状态.
- 已经证明,X射线辐射可以在*大肠杆菌*DHFR中驱动二基酸盐的部分减少为四基酸盐.
- 化物转移诱导了NADP+尼古丁胺部分的运动和相关的残留物转移,更高的剂量会影响大肠杆菌*DHFR中的Met20构造.
- 与大肠杆菌DHFR相比, *B. subtilis* DHFR表现出明显的形状异质性和不寻常的二硫化键.
结论:
- X射线辐射可以诱导细菌DHFR中的化物转移,模仿本地催化反应.
- X射线光还原提供了一种新的方法来探测具有催化作用的相关酶动态.
- 在 * Bacillus subtilis * 和 * E. coli * DHFR 之间存在显著的结构和动态差异,影响它们的功能和作为药物点的潜力.
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